A few weeks back, two Republican caucus-goers in different Iowa cities told me basically the same thing. One called Newt Gingrich “a bully.” The other called him “a little tiger.” In both cases, the comments were compliments. Like most Republicans, they liked Gingrich when he acted like an ornery pugilist. But at the time, their comments seemed almost nostalgic. Remember, this was Iowa, back when Newt Gingrich was in his full, self-pitying victim mode. “I feel Romney-boated,” he complained, sounding like the John Kerry, circa 2004, more than Gingrich the fighter. His public posture was essentially the one that of a cowed math geek; he held his head high in the hopes that the correctness of his formulas would matter more in the end than all the locker room wedgies.

In other words, Gingrich had given up one of his best traits. The bully had been bullied. But he learned his lesson. After Iowa, Gingrich found his inner fighter and started punching. “You either have to unilaterally disarm and leave the race, or you have to at least bring up your competitor’s record,” he said in last week’s Myrtle Beach debate. And South Carolina voters fell in love with the bully–the way he showed up CNN’s John King and Fox News’s Juan Williams, the way he ripped Barack Obama as a food stamp President, and described Romney as a high finance opportunist.

This wasn’t the only change. In Iowa, Romney, a spreadsheet jockey, played the bully. It had been his friends, after all, that caught Gingrich off guard, hammering him with vicious attacks. When Romney was asked about Gingrich’s protestations, his response was cool. “There is a lot of heat in the campaign kitchen,” Romney said. “I know the speaker is angry. I don’t know why.” It was a deadly line. And it worked. There was only one alpha dog in Iowa, even if he lost the final caucus vote count.

But the Romney of South Carolina was something different. He still talked tough about Barack Obama, but seemed baffled by Gingrich. He whined, like Gingrich, about the inaccurate ads paid for by Gingrich’s friends, and when asked simple questions about his finances, he acted like this was none of anybody’s business. The alpha became the beta, and the beta in Republican politics always loses. Almost always.

Polls don’t do a good job of tracking this x-factor. But it will be a thing to watch now that the campaign is moving to Florida and beyond. A certain percentage of the Republican electorate will vote for the toughest pugilist, the one who channels the Grand Old Party’s id. It is still not clear who that will be.